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  Wire/fiber ring and method for manufacturing the sameUSPTO Application #: 20070068619Title: Wire/fiber ring and method for manufacturing the same Abstract: A wire/fiber ring having two layers applied in four clock positions. Each layer includes a first material strand having a first diameter and a second material strand having a second diameter different from the first diameter. A second or any subsequent layer is disposed such that there is unambiguous nesting between strands in adjacent layers. After the array is built-up, wire is over-wrapped around the array to hold it in place during subsequent consolidation steps, which take place after the built-up array is sealed in an air-tight container and evacuated. After heating and application of pressure a wire/fiber array having a void content of about 12% and a fiber content of between about 0% to 70% and preferably between about 30% and 45% can be achieved. (end of abstract) Agent: Nixon & Vanderhye, PC - Arlington, VA, US Inventors: William Hanusiak, Lisa Hanusiak, Steven Spear, Charles Rowe, Jeffery Parnell USPTO Applicaton #: 20070068619 - Class: 156173000 (USPTO) Related Patent Categories: Adhesive Bonding And Miscellaneous Chemical Manufacture, Methods, Surface Bonding And/or Assembly Therefor, Bonding Of Flexible Filamentary Material While In Indefinite Length Or Running Length, With Winding Of Filamentary Material, Winding About Subsequently Removed Core Or Mandrel The Patent Description & Claims data below is from USPTO Patent Application 20070068619. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] The present invention is directed to wire/fiber rings, and more particularly to an improved matrix composite wire/fiber ring having improved void and fiber fractions, and a method of manufacturing the improved matrix composite wire/fiber ring. BACKGROUND AND SUMMARY OF THE INVENTION [0002] Titanium matrix composite (TMC) rings are useful in high temperature rotating parts, such as turbine engines, where specific stiffness and strength are critical to design. While affordability issues generally have hampered the use in production of these materials, one TMC fabrication method has shown promise. According to this method titanium wire and silicon carbide (SiC) fiber are combined to form a hoop reinforcement array. Methods for fabricating TMC rings in this way have been described in U.S. Pat. No. 5,763,079 to Hanusiak et al. and U.S. Pat. No. 5,460,774 to Bachelet. These two patents describe different approaches to achieve the same end. However, both also restrict manufacturing flexibility in ways critical to design. [0003] The method described by Hanusiak et al. is illustrated in FIGS. 1A-1C. In this approach, the combination of wire 3 and fiber 4 is restricted to a one-to-one ratio, but the wire diameter and the fiber diameter can be different as long as the wire 3 diameter is greater than that of the fiber 4. The selection of wire and fiber diameter establishes the fiber fraction in the resultant composite. For example, using a 0.007 inch diameter wire and a 0.0056 diameter fiber results in a composite with a fiber fraction of 30%. In accordance with Hanusiak et al., the assembly consists of one tape containing all wire elements and one tape containing all fiber elements combined to form two layers per ply. Each tape is made up of equal-sized elements, but the elements in the first tape do not have to be the same size as the elements in the second tape. The assembly is built up using alternate tapes of each type applied to a winding core in such a way that adjacent fibers 4 do not come in contact with each other. The advantage of the structure according to Hanusiak et al. is that the ratio of wire-to-fiber diameters can be varied such that composites with fiber fractions between 35% and 45% can be readily fabricated. Such a range of fiber fractions is particularly desirable for effective ring construction. The disadvantage of the structure according to Hanusiak et al., however, is that the assembled array contains about 20% void, which is particularly detrimental in thick parts because it allows for undesirable cusp formation during metal movement. Moreover, the structure according to Hanusiak et al. has been shown to be organizationally unstable during a consolidation cycle to remove the void content of the TMC part. [0004] FIG. 1A shows a cross-section of a composite ring structure 1 according to Hanusiak et al. wherein there is maximum fiber spacing such that wires 3 touch in the height direction only. FIG. 1B shows an embodiment in accordance with Hanusiak et al. wherein there is median fiber spacing such that the fibers are spaced equally in width and in height. FIG. IC depicts yet another configuration of a structure in accordance with Hanusiak et al. wherein there is minimum fiber spacing and wires 3 touch each other in the lateral or width direction only. [0005] The method described by Bachelet is illustrated in FIGS. 2A-2C. According to Bachelet, the wire/fiber combination is restricted to a two-to-one or a three-to-one ratio. Additionally, in all of the examples disclosed by Bachelet, the wire diameters are limited to the same dimension as the fiber diameters. All assemblies utilize two layers per ply and fall into three types as shown in FIGS. 2A-2C. [0006] Specifically, as shown in FIG. 2A, each layer is made up of fibers 4 separated by two equivalent-diameter wires 3, and the second layer is laterally indexed so that the fibers 4 nest between the two wires 3 in the layer below. [0007] In other variations of the Bachelet structure, as shown in FIGS. 2B and 2C, one layer is made up of fibers 4 separated by one equivalent-diameter wire 3. The second layer is made up of all wires 3 of the same diameter as the fibers 4 in the first layer. The advantage to the Bachelet approach is that the void content is only about 10%, and the array apparently is organizationally stable during subsequent consolidation steps. Furthermore, the Bachelet approach, because of the resulting relatively low void fraction, may be desirable for thick parts since there is a lower tendency for cusp formation along the TMC perimeter. The disadvantage, however, of the Bachelet approach is the limitation in the examples to equal diameters for the wires and fibers, which limits the fiber fraction to 25% or 33%. These fiber fractions are not in the most desirable range from a design standpoint. That is, in many designs, a 40% fiber fraction is desirable to achieve a useful performance increase. [0008] Additionally, all examples disclosed in the Hanusiak et al. and Bachelet patens are limited to equal-sized elements in any single layer. Although those references do not specifically exclude the case where elements in a layer may have different diameters, neither reference addresses the special problems associated with such a structure. Namely, when dissimilar-sized elements are provided in a single layer and all elements in a layer are applied to the winding core simultaneously there occurs an inherent stacking, or organizational, instability. [0009] It is noted that simultaneous application of all elements in any single layer is a specific requirement of Bachelet. Bachelet apparently applies this constraint to control the element spacing in the first layer, since the reference fails to describe any other method for spatially controlling elements in the first layer on a winding mandrel. This also implies that the elements in the first layer are touching in order to effectively fulfill the positioning goal. Subsequent layer element positions are thus defined by gaps created between elements in the first layer. Given a first layer with touching elements, and dissimilar wire and fiber diameters, subsequent layer elements will typically lose their track due to nesting site ambiguity and the assembly will fall into disarray. FIGS. 3A-3C depict how a second layer of non-equal sized elements might be disposed on a first layer of non-equal sized elements and how, ultimately, after several layers have been applied, substantially all order is lost (FIG. 3C). That is, the non-equal element size in a given layer creates competition for nesting sites if the subsequent layer elements arrive at the same time. [0010] Thus, there is a need for an improved method for achieving low void content in a stable array, concurrently with flexibility in fiber fraction between about 0% to 70% and preferably between about 30% and 45%. SUMMARY OF THE INVENTION [0011] Accordingly, it is an object of the present invention to provide an improved TMC wire/fiber ring structure and a method of manufacturing the same wherein there is an unambiguous position choice for each element in each layer. [0012] It is a further object of the invention to provide a TMC wire/fiber ring that is low in void and has fiber fraction within a desirable range. [0013] It is a further object of the present invention to provide a TMC wire/fiber ring that comprises elements of different diameters in a single layer. [0014] It is still another object of the present invention to provide a winding mandrel that provides unambiguous positions for a first layer of wire and/or fiber. [0015] Another object of the present invention is to define and implement a hardware set and associated elements to achieve a stable and efficient consolidation process. [0016] To achieve these and other objects, the present invention provides a composite ring having as a first layer a plurality of first strands or elements each having a first diameter and being spaced from each other with a predetermined distance. A plurality of second strands each having a second diameter different from the first diameter, are disposed such that at least two of the second strands fit between adjacent first strands, thereby completing the first layer. [0017] As a second layer, a plurality of third strands having the same diameter as the first strands are disposed offset from the first strands such that the third strands overly a region between the second strands in the first layer. Finally, a plurality of fourth strands having the same diameter as the second strands, are disposed offset from the second strands such that a region between adjacent fourth strands is disposed over the center of the third strands. The resulting overall configuration is a two layer structure obtained with four tapes, i.e., four sets or bundles of strands. [0018] In a preferred embodiment of the invention, the first, second, third and fourth strands comprise at least one of fiber and wire. The fiber preferably comprises silicon carbide and the wire preferably comprises titanium such that a TMC wire/fiber ring is obtained. [0019] Also in accordance with the present invention, the fiber strands preferably have diameters larger than the wire strands. Such a construction results in a fiber fraction of approximately between 30% and 45% and a void fraction of about 12%. [0020] In a preferred embodiment of the method in accordance with the present invention, a mandrel having grooves that correspond respectively to desired locations for each strand of the first layer is provided for winding the TMC part. Accordingly, nesting sites in the first layer are properly arranged for the second and any subsequent layers. Alternatively, "grooves" can be achieved by providing on the mandrel a layer of wire having a selected diameter, resulting in predetermined nesting sites, consistent with the desired spacing for the first strand layer. [0021] In accordance with the method of the present invention, tapes comprising the plurality of strands are wound simultaneously, but each tape is applied to the mandrel at different tangential, or "clock," positions. Winding is continued until the desired thickness is achieved. In accordance with preferred embodiments, the strands may or may not contact each other in a lateral direction. [0022] Further in accordance with a preferred embodiment of the present invention, after winding is complete an exposed layer of the strands preferably is over-wrapped with over-wrap wire to preserve the array pattern. Continue reading... Full patent description for Wire/fiber ring and method for manufacturing the same Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Wire/fiber ring and method for manufacturing the same patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. 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